Both series are microprocessor controlled with
adjustable capacitor voltages from 50v to maximum (in 1v steps) with
feedback via a digital display. The microprocessor controls the
charging and discharging of the machine ensuring that the charging is
managed in a way to reduce the initial charge current that
non-microprocessor systems may not have. The microprocessor also
performs fault monitoring for system protection.
Each magnet charger demagnetiser is fitted with an
internal dump resistor to discharge the main capacitors in power down
or abort mode, ensuring a safe environment for both operator and
All MCD units have the ability to interface with
external PLC controllers via a digital interface as well as an RS232
port for integration with other products such as Integrating Fluxmeters
The MCD series (as defined by the energy output, in
joules, to the demagnetising fixture i.e. MCD4kJ), which is based on
electrolytic capacitor technology, is suitable for low and medium
production rate. The typical range of energy outputs for the
series span from 750J to 20kJ, at capacitor voltages of up to 800 volts.
The MCDa series, which uses non-electrolytic capacitors,
is capable of high production rates. The typical range of energy
outputs for the above series span from 100J to 20kJ, at capacitor
voltages of up to 3,000 volts.
Principles of operation
In most applications, the required current is too large
to be directly driven from the mains and/or the fixture’s
inductance/resistance is such that not enough current would flow to
produce the required magnetic field. A capacitor bank is
charged to the required voltage level (up to 3,000 volts) and this
stored energy is then discharged by a thyristor into the fixture to
produce the required magnetic field.
In a magnetising operation a clamp or freewheel diode
may be placed across the fixture to ensure no reverse energy charges
the capacitor bank negative. All the energy is dissipated into
fixture as a magnetisation pulse. Some MCD series units may not
freewheel diode and only apply a unidirectional pulse.
For the setting operation the capacitor bank is again
charged, to a lower voltage level, and this time the energy is fired
through the fixture in reverse. Only a unidirectional pulse is
This partially drives the magnet down its demagnetisation curve.
Ignitron outputs will be offered instead of
semiconductor devices if the peak current is exceedingly high and/or
the rise time of the pulse is very short.
Ignitrons may also be offered for machines where the
fixture is “unknown” or where fault conditions are expected that could
damage semiconductor output devices.
Both MCD and MCDa series features an easy to use control
panel that includes:
Four Buttons Operation Control
Pulse (Green) – to initiate a magnetisation cycle
Abort (Red) – to abort the current sequence
Up and Down (Yellow) – allows the adjustment of
LCD display – shows the current voltage level, status
and error messages
Key switch – available as an option to lock the
PLC interface – allows integration with automated
RS232 interface – optional extra
Magnet Charger Demagnetiser Energy
Magnet charger demagnetiser energy will be selected to
meet the requirements of the application and will be dependent on the
fixture design. Typically, due to the high cost of energy storing
capacitors, the higher the energy needed to satisfy the magnetising
application, the higher the cost of the equipment.